javascript

CHAPTER 9 ■ LISTENING FOR EVENTS
the Brooks , the would follow their mouse. They’d never be able to click the Brooks —or any
other link on the page. Great googly moogly, we can’t have that!
Let’s register drop() on document, too. Pass true for the fourth parameter again to improve
performance in Internet Explorer 9, Firefox, Safari, Chrome, and Opera. Rather than wait for the
mouseup event to descend and ascend the DOM tree, just nip it in the bud:
function drag(e) {
if (!e) e = window.event;
if (!e.target) e.target = e.srcElement;
var wrapper = e.target.parentNode;
var left = parseInt(queryCascade(wrapper, "left"));
var top = parseInt(queryCascade(wrapper, "top"));
var clientX = e.clientX;
var clientY = e.clientY;
wrapper.style.zIndex = doZ();
addListener(document, "mousemove", move, true);
addListener(document, "mouseup", drop, true);
function move(e) {
if (!e) e = window.event;
}
function drop(e) {
if (!e) e = window.event;
}
}
Now call burst() and thwart(), remembering to pass in e, which contains the mousedown event
object. Doing so prevents any mousedown event listeners bound to ancestors of the from running
and a context menu from appearing for Mac visitors:
function drag(e) {
if (!e) e = window.event;
if (!e.target) e.target = e.srcElement;
var wrapper = e.target.parentNode;
var left = parseInt(queryCascade(wrapper, "left"));
var top = parseInt(queryCascade(wrapper, "top"));
var clientX = e.clientX;
var clientY = e.clientY;
wrapper.style.zIndex = doZ();
addListener(document, "mousemove", move, true);
addListener(document, "mouseup", drop, true);
burst(e);
thwart(e);
function move(e) {
if (!e) e = window.event;
}
function drop(e) {
if (!e) e = window.event;
}
}
We’re done with the mousedown event listener. Now let’s move on to move(), mousemove event
listener. Sorry for the pun.
379